Generalized reversible susceptibility tensor

Abstract

A theory of reversible susceptibility tensor based on magnetization vector dynamics, as described by the Landau–Lifshitz equation of motion, is given. It is shown that the reversible transverse susceptibility (RTS) is in fact the zero frequency limit of the ferromagnetic resonance (FMR). Thus, the methods which have been developed previously for the theoretical description of FMR may be applied to predict the RTS behavior. The importance of these results resides in the generality of the approach which allows one to find the reversible susceptibility tensor for virtually any magnetic system if an expression for the magnetic free energy density is known.